From lathes to 3D printers
Prototypes have become an indispensable part of product development. Thanks to modern 3D printing processes, they can be produced faster and more cost-effectively than ever. But the time it takes to deliver the models plays an increasingly important role in their success. More and more prototypes are also being equipped with (electric) drive mechanisms. Three experts from PCV Group in Enschede, in the Netherlands, shine some light on current trends in prototyping.
The press of a button rather than a lathe: 3D printing has revolutionised the development of prototypes. “The different 3D printing processes available offer countless possibilities”, explains Wouter Nijland, Lead Engineer at PCV Group. He sees the fact that the printed prototypes already look like the actual finished products as a huge advantage. “The prototype is produced with a logo, labelling and the desired functions, so you have an almost exact copy of the future original in your hands.” And most importantly, we can physically hold it and test how well it works at an early stage. This is an invaluable advantage compared to conventional methods and means that the ergonomics and ease of use of different designs for a product can be assessed quickly and easily.
Another example is that of a coffee machine filled with capsules, where the task was to transport the used capsules away completely automatically during the brewing process. To achieve this, around 40 different parts had to be considered, including automatic grippers. Due to this complexity, it was particularly important to create a model that was faithful to the original, in order to simulate the subsequent behaviour of the capsules. Thanks to 3D printing, these challenges could be overcome.
“When we are working in the pre-development stages, we don't yet have a design for the final product. But we can suggest what it might look like by using 3D printing. The advantage of this is that we can include components such as the motor or pumps in what we consider to be the right positions”, Nijland explains. “This means that our customers can see that we have the technical aspects in hand, and that's why they hire us. But with the right design and architecture, we can still surprise them.”
Selective laser sintering
Which 3D printing processes are used at PCV Group? As the engineers explain, it depends on the specific project. “Most often, we use selective laser sintering and a relatively new process called multi-jet fusion”, explains Nijland. The two methods use different approaches to build up a new workpiece layer-by-layer starting from a powder. As the material for the model does not have to be the same as the material for the actual product, nylon is frequently used, often with suitable additives to increase its strength. “We can also print with metals, but that is expensive and takes more time.”
Other PCV colleagues are also very interested in these 3D printing processes. “Whenever a freshly printed prototype is delivered, a number of engineers will take a look and discuss the result. As technical engineers, we are all simply curious and have a natural interest in it. This also means that we can learn from each other at the same time.” Speaking of colleagues, for each order, PCV assembles a project team bringing together the required specialists, such as experts in electronics.
“More and more prototypes now include a drive mechanism. And this means that the electronics also play a greater role in prototyping,” says Senior Engineer Neal Meijers, describing another trend. The PCV Group is proactively pursuing this development. "Our roots are in the field of mechanical construction, but for some years now we have been developing our expertise in the area of electronics.” Meijers is one of the PCV engineers specialising in this field.
His tasks range from small, simple prototypes to complex high-end devices. The smaller tasks include things such as an inhaler fitted with a small printed circuit board (PCB). “At the other extreme, we have a coffee machine, for example. This project involved documenting the detailed behaviour of coffee beans”, explains Neal Meijers. Using high-frequency measurements, we wanted to study how the coffee beans and the grinder interact. Based on these results, we managed to find the perfect setting for the grinder. This was a complex project, but one that ultimately led to the desired success – thanks to the electrical engineering expertise of the PCV team. One particularly useful aspect is that “We put together the prototypes ourselves in house”, explains Neal Meijers.
When it comes to assembly, this is one of the key areas of expertise for Sebastian Kass, a German engineer at the Dutch company. “For me, precision is the most important thing. If we’re just carrying out small tests with a few tubes and a small aluminium frame, it's not crucial. But when we have complex prototypes for end products, attention to detail at the start makes things a lot easier further down the line.”
On the other side of the coin, this has to be balanced against an increasingly important customer requirement: “It's got to be quick. The delivery time is critical. Sometimes higher costs are acceptable if it means that the model comes back quicker as a result.” The production of a prototype usually takes one to two days. “We also once had a complex project to develop a visual and functional model of a coffee machine. We worked on that for six weeks, but that was an exception”, Kass explains.
One thing that increases the speed and therefore reduces delivery times is quick 3D printing. “With one partner, we can print over the weekend if we send the specifications by noon on Friday. We have another partner that exclusively prints models for us. If we send them the required data by 6 pm, we can have the product by the following morning.” Instead of powder, this technique uses a liquid resin as the starting material, which is exposed with a laser and then fully cured using UV light. These printed prototypes often have to be reworked, especially if they are housing parts.” For this purpose, PCV Group has its own workshop with a lathe and milling machine, run by a master craftsman.
The route from modelling to series production can sometimes be a complex one. “When I sketch a design, I will already have the manufacturing process in mind. From design to assembly, prototyping is a process in which all the cogs have to mesh together. We mainly work in pre-development. The point at which we pass the baton to series production, as it were, depends on the project.” The later we do so, the more challenging – and thus more attractive for the PCV engineers – it is. Which is why they are always keeping one eye on the latest trends...